In this article, we introduce a method for using a smartphone to estimate the bi-directional reflectance distribution functions of real-world surfaces. Specifically, we use a combination of image-based and visual techniques to determine a surface's diffuse and specular reflectance parameters in the Ward light reflection model. We test the accuracy of the method by comparing our estimates to instrumental measurements of color and gloss standards. We demonstrate its utility by rendering synthetic images of method-estimated surfaces and comparing the renderings with photographs of the real surfaces. The method provides a lightweight approach to surface reflectance measurement. © 2018 Society for Imaging Science and Technology.